-LRB- CNN -RRB- For Formula One fanatics it was a thrilling spectacle -- the sport 's top two drivers going head-to-head for the drivers ' championship title .

That Nico Rosberg and Lewis Hamilton were teammates , from the Mercedes stable , made it all the more enthralling .

Not only did they go corner-to-corner on the circuit , they also traded verbal volleys away from the pit lane .

For Rosberg , who was ultimately beaten to the world title by the Briton and had to deal with plenty of criticism along the way , it was n't the first time he 'd felt like an outsider .

As testing for the 2015 season continues , he says last term provided some trying moments but he insists he ca n't think of a better teammate than Hamilton .

`` Of course there have been clouds , '' he told Formula One 's official website . `` Everybody has his own relative worries .

`` I was treated pretty badly by the other kids in my early school years . I was traveling a lot with my parents , so I never belonged to a gang -- I was always the outsider .

`` Later in life I discovered the beauty of traveling , but as a small kid I hated it -- I wanted to be part -LSB- of things -RSB- . This might sound like small fry , but a seven-year-old takes that very seriously .

`` But also my racing career was cloudy at times : my two Formula Three years when I did n't go anywhere and my Formula One dream almost became elusive . And even in Formula One I had tough periods .

`` I wanted to win and had been driving so many years behind , seeing the others having these awesome cars -- Lewis in the early days at McLaren and Vettel at Red Bull -- and I was just driving behind .

`` Sure it was not suffering in any way , but for me individually I want to win and if I do n't win it sucks . But I am not dwelling on the past . One day after Abu Dhabi my life was back to normal . ''

Prior to last season 's runner-up berth , Rosberg 's best finish in an F1 season was sixth back in 2013 .

But once it became clear 2014 's spoils were a straight contest between the German and Hamilton , cracks began to appear in their relationship , which began back in their teenage years .

It reached a nadir at the Belgian Grand Prix , when the pair -- who were allowed to develop a fiercely competitive rivalry by their team -- collided early in the race .

Hamilton was later forced to retire and told reporters after the race Rosberg had admitted to crashing into him on purpose .

The 29-year-old was blamed by Mercedes , fined and made to apologize , Hamilton going on to win six of the last seven races to claim his second F1 crown .

But despite the negative press their spat engendered last term , Rosberg thinks its tempestuous nature is likely to continue in 2015 .

`` We have a relationship that goes up and down and it will continue to go up and down , '' he explained . `` It is an intense battle between us and that will not change any time soon .

`` Last year 's experience helps . It 's that ` been there , done that ' kind of thing . All the difficult times have made me stronger . It is the difficult moments where I learn the most .

`` Of course with time , and the situation , the skin grows thicker . Yes , there have been challenging times , but from my point of view I always felt comfortable , and it continues like that . ''

When asked if he could think of a better teammate to have than Hamilton he replied : `` No . It is the challenge that I relish . ''

Mercedes ' decision to permit their two drivers to go hell for leather in pursuit of the F1 title was questioned in some quarters , especially after that flashpoint in Belgium .

But according to team principal Toto Wolff , that modus operandi and the tension it brings can help spur his drivers onto greater heights .

`` We chose a strategy of ` let them race , ' '' he explained . `` For a team it is better to have two equally good drivers trying to beat each other but also sharing data with each other .

`` That is when a team is getting pushed forward . The downside -- the intense competition -- we will live with . We have learned from last season . We have matured as a team , including the drivers .

`` Yes , I have no illusions that 2015 will be an easier year . There will again be times of discussion , sure . But these are the situations that bring you to the front . ''

Wolff says everyone at Mercedes is hungry to replicate last season 's success , in which it won the drivers ' and constructors ' championship .

And while admitting this season could see greater competition from the likes of Ferrari and Red Bull , he would n't be drawn on which of his drivers has the edge going into the new season .

`` Before we start that discussion : we have to provide them with a car that gives them the tool to fight for the championship , '' he said .

`` They had a very intense battle last year and I have no doubt that if they have a good car they will be fighting for wins and the championship again .

`` But honestly I do n't see 2015 as a runaway season for one of the two -- so there will be lots of ` excitement ' for the team and another sizzling season for the fans . ''

Wolf also said he had no concerns about Hamilton 's contract , which is entering its final season .

`` We are having discussions -- very positive ones , which will come to a positive end soon . I have no doubt about that , '' he said .

`` We met each other after the break one week ago and had a good discussion . There is no hurry . It 's only January and his contract runs for another year .

`` So when we discuss , it 's still about something that 's happening in 12 months . No stress . We want him to stay and he wants to stay , so there are no risks in taking the situation calmly . ''

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Mercedes ' Nico Rosberg admits to dark times during the 2014 F1 season

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But the German says he overcame disappointment of finishing second immediately

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Rosberg and F1 champion Lewis Hamilton had fractious relationship last season

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The 29-year-old says their partnership will continue to be an intense one